Development of an analytical method to determine malondialdehyde as an oxidative marker in cryopreserved bovine semen

Frozen sperm is widely used in artificial insemination of cattle as well as other animal species. As a consequence of the freezing and thawing processes of semen, an excess of reactive oxygen species (ROS) are formed. ROS produce oxidative damage in sperm cells affecting both motility and fertility. Malondialdehyde (MDA) is one of the most recognized biomarkers of an advanced oxidative status. MDA was analyzed after its condensation reaction with thiobarbituric acid (TBA); however, other molecules can also react with TBA. In order to determine specifically the MDA–TBA2 condensation product in cryopreserved bovine semen, a sensitive and selective separation strategy was developed using high performance liquid chromatography (HPLC) with diode array detection (DAD). This is the first report on MDA determination in bovine semen by a separation method. Different methodological approaches were assayed. Treatment A directly measured total MDA through acidic hydrolysis combined with TBA condensation in a single step. Treatment B evaluated separately the TBA condensation product of free MDA and protein bound MDA after its release with alkaline hydrolysis. The highest concentration of MDA was detected following treatment A. An HPLC method was developed and validated by comparing with the traditional spectrophotometric method. The detection and quantification limits were 0.034 μM and 0.086 μM. The DAD response was linear in the range between 0.086 and 9.1 μM. The recovery was 91%. The intra- and inter-day relative standard deviations were 3.7 and 3.8%, respectively. The proposed HPLC method was markedly more sensitive and more specific than the traditional spectrophotometric one.Fil: Yonny, Melisa Evangelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; ArgentinaFil: Reineri, Pablo Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; ArgentinaFil: Palma, Gustavo Adolfo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Tucumán-Santiago del Estero. Estación Experimental Agropecuaria Santiago del Estero; ArgentinaFil: Nazareno, Mónica Azucena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; Argentin

Could Fire Severity Promotes the Biosynthesis of Bioactive Compounds as a Strategy to Improve Plant Survival?

Fire has effects on diverse aspects of plant functioning and development, many of themlinked to survival. However, the response of native vegetation to this disturbance possibly revealsa plant strategy to tolerate fire linked to the biosynthesis of compounds such as chlorophylls andsecondary metabolites. The aim of this study was to evaluate whether fire severity could promotebiochemical tolerance to fire by influencing the biosynthesis of chemical compounds. To test this,six woody species from the Chaco region were exposed to an experimental burn of medium severityat the end of fire season in the study area. In this burn, individual plots for each plant were established. Fire severity was estimated visually as the burnt biomass of each plant, which was considered as the percentage of the loss of aboveground biomass. Then, the biochemical plant response tofire was studied, through the changes in the concentration of photosynthetic pigments (chlorophylland carotenoids), and secondary metabolites (phenolic compounds and tannins). The metabolitequantification was carried out by using spectrophotometric methods. As a result, a strong correlation was found between the biosynthesis of metabolites in response to fire and the amount of burntbiomass during the experimental burns. This correlation could be considered as an indicator of theburnt plant response to stress. In our results, shrubby species showed both the higher amount ofburnt biomass and the enhanced biosynthesis of compounds in the resprouts post-fire, which couldbe related to the capacity of these species to be established in disturbed environments. Our studyprovides new insights into the understanding of the plant strategies to fire tolerance and resiliencein natural environmentsFil: Santacruz García, Ana Carolina. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias. Instituto de Ciencias Químicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Nazareno, Mónica Azucena. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias. Instituto de Ciencias Químicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Bravo, Sandra. Universidad Nacional de Santiago del Estero. Facultad de Ciencias Forestales. Instituto de Silvicultura y Manejo de Bosques; Argentin

Suplementação de grãos de destilação secos com solúveis melhora a utilização de grama tropical de baixa qualidade para novilhos de corte

This study was designed to evaluate the effect of corn dried distiller´s grains (DDGS) supplementation on feed intake, total tractdigestibility, and ruminal fermentation of beef steers fed low-quality Guinea grass (Megathyrsus maximus, cv. Gatton panic). TwelveBraford crossbred steers were housed in individual pens (n = 4 steers/treatment), provided with three levels of DDGS supplement: 0%, 0.6%,or 1.2% BW. Steers were blocked by live weight and randomly assigned to treatments within the block. Corn DDGS supplementation increasedtotal OM intake (21.55, 40.23, and 56.69 g/kg BW0.75) and tract OM digestibility (46.33, 49.03, and 72.39 % DM). Total tract digestible OM,CP, NDF and EE intake also increase in response to DDGS supplementation. Forage OM intake decreased when supplementation level reached1.2 % BW. Also, ruminal pH decreased with DDGS supplementation level (6.88, 6.47, and 6.27). No differences were observed in total volatilefatty acids (VFA) concentration; however, the molar proportion of acetate decreased (77.98, 73.90, and 67.29 % Total VFA) as well as acetate:propionate ratio (4.38, 3.48, and 2.74). On the contrary, propionate proportions increased (18.32, 21.86, and 24.81 % Total VFA). Levels ofammonia and lactate were within suggested values for optimal fermentation and bacterial growth. Low-quality grass supplementation withcorn DDGS increased total OM intake and digestibility. Also, DDGS inclusion favorably altered volatile fatty acids profile by reducing theacetate to propionate ratio regarding forage-only diets.O objetivo deste estudo foi avaliar o efeito da suplementação com grãos de destilação secos de milho com solúveis (DDGS) no consumo, digestão e fermentação ruminal de novilhos de corte alimentados com capim-da-índia de baixa qualidade (Megathyrsus maximus, cv. Gatton panic). Doze novilhos mestiços Braford foram alojados em baias individuais (n = 4 novilhos / tratamento), fornecidos com três níveis de suplemento de DDGS: 0%, 0,6% ou 1,2% PV. Os novilhos foram bloqueados pelo peso vivo e atribuídos aleatoriamente aos tratamentos dentro do bloco. A suplementação com DDGS de milho aumentou o consumo de matéria orgânica total (21,55, 40,23 e 56,69 g / kg PV0,75), a digestibilidade da matéria orgânica (46,33, 49,03 e 72,39% MS) e o consumo de todos os nutrientes digestíveis. O consumo de matéria orgânica da forragem diminuiu quando o nível de suplementação atingiu 1,2% PV. Além disso, o pH ruminal diminuiu com o nível de suplementação com DDGS (6,88, 6,47 e 6,27). Não foram observadas diferenças na concentração de ácidos graxos voláteis totais, no entanto, a proporção molar de acetato diminuiu (77,98, 73,90 e 67,29% de AGV total), bem como a relação acetato: propionato (4,38, 3,48 e 2,74). Pelo contrário, as proporções de propionato aumentaram (18,32, 21,86 e 24,81% Total de AGV). Os níveis de amônia e lactato estavam dentro dos valores sugeridos para fermentação ideal e crescimento bacteriano. A suplementação de gramíneas de baixa qualidade com DDGS de milho aumentou o consumo e a digestibilidade da MO total. Além disso, a inclusão de DDGS alterou favoravelmente o perfil de ácidos graxos voláteis, reduzindo a proporção de acetato para propionato em relação às dietas apenas com forragem.Fil: Hernández, Olegario. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: López, Agustín. Instituto Nacional de Tecnología Agropecuaria; Argentina. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias; ArgentinaFil: García, Elisa Mariana. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nazareno, Mónica Azucena. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Arroquy, Jose Ignacio. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Cesáreo Naredo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Seasonal isothiocyanates variation and market availability of Brassicaceae species consumed in Mendoza

Along with the recommendation of a healthy diet, it is suggested to increase the consumption of fruits and vegetables. Among the latter, Brassicaceae species are preferred, because they show many phytochemicals mainly belonging to the isothiocyanates (ITCs) family compounds, with proven activities related to the prevention of chronic diseases and cancer. A survey about seasonal availability and phytochemical levels of Brassicaceae species in the total of vegetables marketed in the province of Mendoza (located in the centre west of Argentina) was done. Results throw that Brassicaceae vegetables are an important part of Mendoza vegetable market reaching up to 23% of the vegetables commercialized. Regarding ITCs content, watercress and rocket were the vegetables with the highest ITCs levels, being, therefore, the most promising vegetables studied herein by their potential functional activities. Finally, high levels of variation (up to 10 times) on ITCs content along the year in a single species were found. These facts should be considered when designing Brassicaceae species phytochemical characterization assays to achieve more reliable results. This work represents the first report of Brassicaceae availability and seasonal phytochemical variability in local conditions. Highlights High levels of variation (up to 10 times) on ITCs content along the year in a single Brassicaceae species were found. Brassicaceae vegetables are an important part of Mendoza vegetable market reaching up to 23% of the vegetables commercialized. Considering ITCs content, watercress and rocket were the vegetables with the highest ITCs levels.Along with the recommendation of a healthy diet, it is suggested to increase the consumption of fruits and vegetables. Among the latter, Brassicaceae species are preferred, because they show many phytochemicals mainly belonging to the isothiocyanates (ITCs) family compounds, with proven activities related to the prevention of chronic diseases and cancer. A survey about seasonal availability and phytochemical levels of Brassicaceae species in the total of vegetables marketed in the province of Mendoza (located in the centre west of Argentina) was done. Results throw that Brassicaceae vegetables are an important part of Mendoza vegetable market reaching up to 23% of the vegetables commercialized. Regarding ITCs content, watercress and rocket were the vegetables with the highest ITCs levels, being, therefore, the most promising vegetables studied herein by their potential functional activities. Finally, high levels of variation (up to 10 times) on ITCs content along the year in a single species were found. These facts should be considered when designing Brassicaceae species phytochemical characterization assays to achieve more reliable results. This work represents the first report of Brassicaceae availability and seasonal phytochemical variability in local conditions. Highlights High levels of variation (up to 10 times) on ITCs content along the year in a single Brassicaceae species were found. Brassicaceae vegetables are an important part of Mendoza vegetable market reaching up to 23% of the vegetables commercialized. Considering ITCs content, watercress and rocket were the vegetables with the highest ITCs levels

Recomendaciones de consumo para aprovechar los fitoquímicos bioactivos presentes en Brassicaceae a lo largo del año en Argentina

El consumo de frutas y hortalizas es recomendado para mantener una dieta saludable. Dentro de las hortalizas, las especies de la familia Brassicaceae se destacan por poseer grandes contenidos de diversos fitoquímicos que han demostrado su acción en la prevención de enfermedades crónicas y cáncer. En el presente trabajo, se realizó un relevamiento sobre disponibilidad estacional y niveles de fitoquímicos de especies de Brassicaceae considerando el total de hortalizas comercializadas en la provincia de Mendoza (ubicada en centro oeste de Argentina). Los resultados demostraron que los vegetales de la familia Brassicaceae contribuyen de modo importante en el mercado representando hasta un 23% de las hortalizas comercializadas. Respecto del contenido de ITCs (isotiocianatos), los mayores niveles fueron encontrados en berro y rúcula y como consecuencia de ello representan los vegetales más prometedores por sus potenciales propiedades funcionales. Además, se pudo observar que la variabilidad en los niveles de ITCs a lo largo del año en una misma especie, puede ser muy amplia (hasta 10 veces). Por esta razón es que podemos recomendar tener en cuanta la fluctuación estacional al evaluar niveles de fitoquímicos en especies de esta familia. Cabe destacar, que este trabajo representa el primer reporte de la disponibilidad de hortalizas de la familia Brassicaceae y la variabilidad fitoquímica estacional en las condiciones locales.Along with the recommendation of a healthy diet, it is suggested to increase the consumption of fruits and vegetables. Among the latter, Brassicaceae species are preferred, because they show many phytochemicals mainly belonging to the isothiocyanates (ITCs) family compounds, with proven activities related to the prevention of chronic diseases and cancer. A survey about seasonal availability and phytochemical levels of Brassicaceae species in the total of vegetables marketed in the province of Mendoza (located in the centre west of Argentina) was done. Results throw that Brassicaceae vegetables are an important part of Mendoza vegetable market reaching up to 23% of the vegetables commercialized. Regarding ITCs content, watercress and rocket were the vegetables with the highest ITCs levels, being, therefore, the most promising vegetables studied herein by their potential functional activities. Finally, high levels of variation (up to 10 times) on ITCs content along the year in a single species were found. These facts should be considered when designing Brassicaceae species phytochemical characterization assays to achieve more reliable results. This work represents the first report of Brassicaceae availability and seasonal phytochemical variability in local conditions.Fil: Fusari Gómez, Cecilia Mara. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias; ArgentinaFil: Beretta, Hebe Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Locatelli, Daniela Ana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias; ArgentinaFil: Nazareno, Mónica Azucena. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias. Instituto de Ciencias y Tecnologías Alimentarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Camargo, Alejandra Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; Argentin

Discontinuous roughage delivery on digestion, rumen metabolism, feed efficiency and liveweight gain of beef steers fed a concentrate diet

Two experiments were carried out to study the effect of feeding a total mixed ration (TMR) compared to feeding the roughage portion of the diet once every two days and separated of the daily delivered concentrate mixture on dry matter intake, nutrient digestibility, ruminal metabolism, feed efficiency and liveweight gain. In Trial 1, thirty beef steers (Braford and Braford × Criollo; initial BW = 259 ± 27 kg) were used in a 69-d feeding trial. Treatments were: total mixed ration (TMR), and the same proportion of ingredients for the ration but roughage offered once every 2-d and separated from the daily delivered concentrate portion of the diet (REOD). Treatments were arranged in a completely randomized design (three pens/ treatment). In both treatments, daily offered ration had on dry matter basis 90% concentrate and 10% grass hay (Setaria italica). Average daily gain (ADG) did not differ among treatment (1013 vs. 1080 g/d for TMR vs. REOD respectively; SEM = 95 g/d). Dry matter intake was greater in TMR compared to REOD (P < 0.01). Gain to feed ratio tended to be better for REOD than TMR (P = 0.07). In Trial 2, four rumen cannulated steers (Braford) were used in an experiment with a crossover design. Treatments were arranged as a 2*2 factorial design, where the first factor consisted of roughage level (RL): (R14) 14% roughage: 86% concentrate and (R7) 7% roughage: 93% concentrate. The second factor was roughage delivery system (RDS; as it was described for Trial 1): TMR and REOD. There were no RL*RDS interactions for intake and digestion (OM, CP, NDF and starch). Both RL were similar for intake and digestion. Roughage delivery system did not significantly affect intake and digestion of OM, CP, NDF, and starch measured by total fecal collection. Total organic acids (TOA), acetate to propionate ratio (A:P), pH, and rumen ammonia concentrations were not affected by RL and RDS. In conclusion, under the conditions of these trials, steers fed a separated roughage source once every 2-d had similar ADG, and tended to be more efficient compared with TMR. Total tract digestibility and rumen environment traits (pH, VFA, and ammonia) were not affected in response to discontinuous roughage delivery.Fil: Arroquy, Jose Ignacio. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Tucumán-Santiago del Estero; Argentina. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; ArgentinaFil: Nazareno, Mónica Azucena. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; ArgentinaFil: Avila, M.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Tucumán-Santiago del Estero; ArgentinaFil: Garcia, M.. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias; ArgentinaFil: Cervetto, J.. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias; ArgentinaFil: Distel, Roberto Alejandro. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Saravia, J. J.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Tucumán-Santiago del Estero; Argentin

Could Biostimulants with Plant Active Compounds Improve the Tolerance to Oxidative Stress in Prosopis alba (Griseb.)?

Presentado al 2nd International Electronic Conference on Forests—Sustainable Forests: Ecology, Management, Products and Trade. Online | 1–15 September 2021The aim of this work was to explore the potential of four phytoextracts derived from species with recognized antioxidant activity and/or rich in polysaccharides as plant biostimulants of seedlings of Prosopis alba. Malondialdehyde (MDA), an oxidative stress biomarker, was measured at 21 days after the acclimation phase beginning as preliminary results showed a significant accumulation of MDA in rustified seedlings compared with control seedlings at this time. As main results, rustified seedlings sprayed with I. paraguariensis and L. divaricata extracts showed lower MDA concentration than rustified seedlings without any phytoextract application. Both extracts were characterized by their antioxidant activity. These results suggest that natural extracts of I. paraguariensis and L. divaricata could be considered plant biostimulants, reducing oxidative stress biomarkers in P. alba.EEA Santiago del EsteroFil: Santacruz-García, Ana Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias Químicas; ArgentinaFil: Santacruz-García, Ana Carolina. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias. Instituto de Ciencias Químicas; ArgentinaFil: Senilliani, Maria Gracia. Universidad Nacional de Santiago Del Estero. Facultad de Ciencias Forestales. Instituto de Silvicultura y Manejo de Bosques; ArgentinaFil: Gomez, Adriana Teresita. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santiago del Estero; ArgentinaFil: Ewens, Mauricio. Universidad Católica de Santiago del Estero. Estación Experimental Fernández; ArgentinaFil: Bravo, Micaela. Universidad Nacional de Santiago Del Estero. Facultad de Ciencias Forestales. Instituto de Silvicultura y Manejo de Bosques; ArgentinaFil: Abraham, Siria. Universidad Nacional de Santiago Del Estero. Facultad de Ciencias Forestales. Instituto de Silvicultura y Manejo de Bosques; ArgentinaFil: Nazareno, Mónica Azucena. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias Químicas; ArgentinaFil: Nazareno, Mónica Azucena. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias. Instituto de Ciencias Químicas; Argentin

How do plants respond biochemically to fire? The role of photosynthetic pigments and secondary metabolites in the post-fire resprouting response

Resprouting is one of the main regeneration strategies in woody plants that allows post-fire vegetation recovery. However, the stress produced by fires promotes the biosynthesis of compounds which could affect the post-fire resprouting, and this approach has been poorly evaluated in fire ecology. In this study, we evaluate the changes in the concentration of chlorophylls, carotenoids, phenolic compounds, and tannins as a result of experimental burns (EB). We asked whether this biochemical response to fire could influence the resprouting responses. For that, we conducted three EB in three successive years in three different experimental units. Specifically, we selected six woody species from the Chaco region, and we analyzed their biochemical responses to EB. We used spectrophotometric methods to quantify the metabolites, and morphological variables to estimate the resprouting responses. Applying a multivariate analysis, we built an index to estimate the biochemical response to fire to EB per each species. Our results demonstrate that photosynthetic pigment concentration did not vary significantly in burnt plants that resprout in response to EB, whereas concentrations of secondary metabolites (phenolic compounds and tannins) increased up to two years after EB. Our main results showed that phenolic compounds could play a significant role in the resprouting responses, while photosynthetic pigments seem to have a minor but significant role. Such results were reaffirmed by the significant correlation between the biochemical response to fire and both resprouting capacity and resprouting growth. However, we observed that the biochemical response effect on resprouting was lower in tree species than in shrubby species. Our study contributes to the understanding of the biochemical responses that are involved in the post-fire vegetation recovery.Fil: Santacruz García, Ana Carolina. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Bravo, Sandra. Universidad Nacional de Santiago del Estero; ArgentinaFil: del Corro, Florencia Inés. Universidad Nacional de Santiago del Estero. Facultad de Ciencias Forestales. Instituto de Silvicultura y Manejo de Bosques; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: García, Elisa Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santiago del Estero. Universidad Nacional de Santiago del Estero. Centro de Investigaciones y Transferencia de Santiago del Estero; ArgentinaFil: Molina Terrén, Domingo M.. Universitat de Lleida; EspañaFil: Nazareno, Mónica Azucena. Instituto de Investigacion y Estudios En Enseñanzas de Las Ciencias (iieec) ; Facultad de Agronomia y Agroindustrias ; Universidad Nacional de Santiago del Estero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentin

Effect of discontinuous roughage delivery on digestion, rumen metabolism, feed efficiency and live weight gain of beef steers fed a concentrate diet

Two experiments were carried out to study the effect of feeding a total mixed ration (TMR) compared to feeding the roughage portion of the diet once every two days and separated of the daily delivered concentrate mixture on dry matter intake, nutrient digestibility, ruminal metabolism, feed efficiency and liveweight gain. In Trial 1, thirty beef steers (Braford and Braford × Criollo; initial BW = 259 ± 27 kg) were used in a 69-d feeding trial. Treatments were: total mixed ration (TMR), and the same proportion of ingredients for the ration but roughage offered once every 2-d and separated from the daily delivered concentrate portion of the diet (REOD). Treatments were arranged in a completely randomized design (three pens/ treatment). In both treatments, daily offered ration had on dry matter basis 90% concentrate and 10% grass hay (Setaria italica). Average daily gain (ADG) did not differ among treatment (1013 vs. 1080 g/d for TMR vs. REOD respectively; SEM = 95 g/d). Dry matter intake was greater in TMR compared to REOD (P < 0.01). Gain to feed ratio tended to be better for REOD than TMR (P = 0.07). In Trial 2, four rumen cannulated steers (Braford) were used in an experiment with a crossover design. Treatments were arranged as a 2*2 factorial design, where the first factor consisted of roughage level (RL): (R14) 14% roughage: 86% concentrate and (R7) 7% roughage: 93% concentrate. The second factor was roughage delivery system (RDS; as it was described for Trial 1): TMR and REOD. There were no RL*RDS interactions for intake and digestion (OM, CP, NDF and starch). Both RL were similar for intake and digestion. Roughage delivery system did not significantly affect intake and digestion of OM, CP, NDF, and starch measured by total fecal collection. Total organic acids (TOA), acetate to propionate ratio (A:P), pH, and rumen ammonia concentrations were not affected by RL and RDS. In conclusion, under the conditions of these trials, steers fed a separated roughage source once every 2-d had similar ADG, and tended to be more efficient compared with TMR. Total tract digestibility and rumen environment traits (pH, VFA, and ammonia) were not affected in response to discontinuous roughage delivery.Fil: Arroquy, Jose Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Tucumán-Santiago del Estero; Argentina. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias; ArgentinaFil: Nazareno, Mónica Azucena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias. Instituto de Ciencias Químicas; ArgentinaFil: García, Elisa Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias. Instituto de Ciencias Químicas; ArgentinaFil: Cervetto, Juan Jose. Universidad Nacional de Santiago del Estero. Facultad de Agronomía y Agroindustrias; ArgentinaFil: Avila, M.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Tucumán-Santiago del Estero; ArgentinaFil: Saravia, J. J.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Tucumán-Santiago del Estero; ArgentinaFil: Distel, Roberto Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; Argentin